[Federal Register Volume 59, Number 9 (Thursday, January 13, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-345]


[[Page Unknown]]

[Federal Register: January 13, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-NM-224-AD; Amendment 39-8790; AD 94-01-08]

 

Airworthiness Directives; McDonnell Douglas Model DC-9 and C-9 
(Military) Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain McDonnell Douglas Model DC-9 and C-9 
(military) series airplanes. This action requires inspections to detect 
cracking in the ventral aft pressure bulkhead, and repair, if 
necessary. This amendment is prompted by reports of cracking found in 
the ventral aft pressure bulkhead on several airplanes. The actions 
specified in this AD are intended to prevent the propagation of cracks 
in the ventral aft pressure bulkhead, which could lead to failure of 
the bulkhead and subsequent rapid decompression of the airplane.

DATES: Effective January 28, 1994.

    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of January 28, 1994.
    Comments for inclusion in the Rules Docket must be received on or 
before March 14, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 93-NM-224-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    The service information referenced in this AD may be obtained from 
McDonnell Douglas Corporation, P. O. Box 1771, Long Beach, California 
90846-0001, Attention: Business Unit Manager, Technical Publications, 
C1-HDR (54-60). This information may be examined at the FAA, Transport 
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at 
the Los Angeles Aircraft Certification Office, FAA, Transport Airplane 
Directorate, 3229 East Spring Street, Long Beach, California; or at the 
Office of the Federal Register, 800 North Capitol Street NW., suite 
700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: David Y. J. Hsu, Airframe Branch, ANM-
120L, Los Angeles Aircraft Certification Office, FAA, Transport 
Airplane Directorate, 3229 East Spring Street, Long Beach, California 
90806-2425; telephone (310) 988-5325; fax (310) 988-5210.

SUPPLEMENTARY INFORMATION: The FAA has recently received reports of 
cracking found in the ventral aft pressure bulkhead on several 
McDonnell Douglas Model DC-9 series airplanes. Two operators reported 
finding fatigue cracks on four airplanes in both the left- and right-
hand side ventral aft pressure bulkhead web and doublers, between water 
lines (stations) Z=43.000 and Z=74.000. The length of the reported 
cracks found in the webs ranged from 5 inches to 48 inches. The webs of 
each of the cracked bulkheads on the subject airplanes were made of 
2014-T6 material and were 0.042 inch thick. It is suspected that 
fatigue is the cause of the cracks. The affected airplanes had 
accumulated between 73,803 and 83,760 landings at the time of the crack 
findings. In each case, the cracking was found during inspections that 
were outside of the operator's normal maintenance program schedule. 
Currently, there is no requirement for regular inspection of the 
affected area of the bulkhead. Cracking in the ventral aft pressure 
bulkhead web or doublers, if allowed to propagate to a critical length, 
could lead to failure of the bulkhead, extensive structural damage, and 
subsequent rapid decompression of the airplane.
    The FAA has reviewed and approved McDonnell Douglas DC-9 Alert 
Service Bulletin A53-264, dated December 22, 1993, that describes 
procedures for conducting repetitive visual, low frequency eddy 
current, and high frequency eddy current inspections to detect cracking 
in the ventral aft pressure bulkhead. The area of inspection includes 
the upper left and right sides of the ventral aft pressure bulkhead in 
the area of the finger doublers and web between stations Z=34.000 and 
Z=74.000, from the edge of the ventral doorway outboard and upward 
along the edge of the doublers. -
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Model DC-9 and C-9 (military) series 
airplanes of the same type design, this AD is being issued to prevent 
failure of the ventral aft pressure bulkhead due to cracking. This AD 
requires repetitive visual, low frequency eddy current, and high 
frequency eddy current inspections to detect cracking in the ventral 
aft pressure bulkhead. These inspections are required to be 
accomplished in accordance with the service bulletin described 
previously. Any cracks found are required to be repaired, prior to 
further flight, in accordance with a method approved by the FAA. 
Additionally, operators are required to submit a report of initial 
inspection findings to the FAA.
    This is considered to be interim action until final action is 
identified, at which time the FAA may consider further rulemaking.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire. 
Communications shall identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed. -
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 93-NM-224-AD.'' The postcard will be date stamped and 
returned to the commenter. -
    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and is not a ``significant regulatory action'' 
under Executive Order 12866. It has been determined further that this 
action involves an emergency regulation under DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979). If it is determined 
that this emergency regulation otherwise would be significant under DOT 
Regulatory Policies and Procedures, a final regulatory evaluation will 
be prepared and placed in the Rules Docket. A copy of it, if filed, may 
be obtained from the Rules Docket at the location provided under the 
caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 14 CFR part 
39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES -

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended] -

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

94-01-08 McDonnell Douglas: Amendment 39-8790. Docket 93-NM-224-AD.

     -Applicability: Model DC-9 and C-9 (military) series airplanes, 
as listed in McDonnell Douglas DC-9 Alert Service Bulletin A53-264, 
dated December 22, 1993; equipped with a ventral aft pressure 
bulkhead web composed of 2014-T6 material that is 0.042 inch thick; 
certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the aft pressure bulkhead due to cracking, 
accomplish the following:
    (a) For airplanes on which the procedures specified in McDonnell 
Douglas DC-9 Service Bulletins 53-26 and A53-144, or production 
equivalent, have not been accomplished (Group I airplanes): Upon the 
accumulation of 50,000 total landings, or within 30 days after the 
effective date of this AD, whichever occurs later, conduct an 
initial visual, low frequency eddy current, and high frequency eddy 
current inspection to detect cracks in the ventral aft pressure 
bulkhead, in accordance with McDonnell Douglas DC-9 Alert Service 
Bulletin A53-264, dated December 22, 1993.
    (1) If no crack is detected during any of the inspections, 
repeat these inspections at intervals not to exceed 1,500 landings. 
-
    (2) If any crack is detected during any of the inspections, 
prior to further flight, repair in accordance with a method approved 
by the Manager, Los Angeles Aircraft Certification Office (ACO), 
FAA, Transport Airplane Directorate. -
    (b) For airplanes on which the procedures specified in McDonnell 
Douglas DC-9 Service Bulletins 53-26 and A53-144, or production 
equivalent, have previously been accomplished (Group II airplanes): 
Upon the accumulation of 60,000 total landings, or within 60 days 
after the effective date of this AD, whichever occurs later, conduct 
an initial visual, low frequency eddy current, and high frequency 
eddy current inspection to detect cracks in the ventral aft pressure 
bulkhead, in accordance with McDonnell Douglas DC-9 Alert Service 
Bulletin A53-264, dated December 22, 1993.
    (1) If no crack is detected during any of the inspections, 
repeat these inspections at intervals not to exceed 1,500 landings. 
-
    (2) If any crack is detected during any of the inspections, 
prior to further flight, repair in accordance with a method approved 
by the Manager, Los Angeles ACO, FAA, Transport Airplane 
Directorate.
    (c) Within 10 calendar days after accomplishing the initial 
inspection required by paragraph (a) or (b) of this AD, as 
applicable, submit a report of inspection findings, both positive 
and negative, to the Manager, Los Angles ACO, FAA, Transport 
Airplane Directorate, 3229 East Spring Street, Long Beach, 
California 90806-2425; fax (310) 988-5210. The report must include 
the following information: -
    (1) Factory serial number of the airplane;
    (2) Total time and flight cycles on the airplane;
    (3) A detailed description of the discrepancy finding;
    (d) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Los Angeles ACO, FAA, Transport 
Airplane Directorate. Operators shall submit their requests through 
an appropriate FAA Principal Maintenance Inspector, who may add 
comments and then send it to the Manager, Los Angeles ACO.

    -Note: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.
    (e) Special flight permits may be issued in accordance with FAR 
21.197 and 21.199 to operate the airplane to a location where the 
requirements of this AD can be accomplished.
    (f) The inspections shall be done in accordance with McDonnell 
Douglas DC-9 Alert Service Bulletin A53-264, dated December 22, 
1993. This incorporation by reference was approved by the Director 
of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR 
part 51. Copies may be obtained from McDonnell Douglas Corporation, 
P. O. Box 1771, Long Beach, California 90846-0001, Attention: 
Business Unit Manager, Technical Publications, C1-HDR (54-60). 
Copies may be inspected at the FAA, Transport Airplane Directorate, 
1601 Lind Avenue SW., Renton, Washington; or at the Los Angeles 
Aircraft Certification Office, FAA, Transport Airplane Directorate, 
3229 East Spring Street, Long Beach, California; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.
    (g) This amendment becomes effective on January 28, 1994.

    Issued in Renton, Washington, on January 3, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-345 Filed 1-12-94; 8:45 am]
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